Su-35 first flight

[D-Scythe]

But one thing I have to grant Mogatu, is that time sharing beams will provide you with the best perfomance. The time intervals are so small that the targeted aircraft would only move a fraction of an inch since its last tracked position, i.e negligeble difference for guiding wepons.

 

Multiple beams by deviding the tiles decreases range and the gain in precision wont be worth it IMHO.

 

I was thinking more along the lines of potential ECCM applications. Generating multiple, different radar beams might have some useful applications in a heavy jamming environment.

[DarkWanderer]

One little fact: the modules cant turn, they are hard-fixed ;) Changing the direction of the beam is reached by signal timing.

Trying to divide the array of transmitter elements into "groups" with different radiation directions will 1.cause interference 2.require n^2 more operations to process every radar return (n - number of receiving elements).

[tflash]

According to Stimson's Introduction to airborne radar, an AESA has indeed this advantage over a PESA system that it can provide multiple sub apertures with multiple steerable beams. These can have different frequencies. In a PESA you have one transmitter / receiver, after each radiating element you have a phase shifter. This way you get - one - extremely agile beam, so that through time-sharing you can interleave A2G with A2A or do some TWS on multiple targets.

 

In the AESA you have many T/R modules directly after the radiating elements. No more single point-of-failure and the ability to have multiple beams. Of course the computing demands are a magnitude higher, for the reasons cited by DarkWanderer.

 

FOV is always limited to 120°, but of course you could mount many arrays. AESA is certainly the technology to go, but this doesn't mean that any AESA radar today is better than the best PESA or MSA. The Eurofighters' Captor MSA radar e.g. is more performant than the Rafale's PESA. My guess is the Su-35 PESA on a mechanical disk will yield a VERY powerfull beast with quite a good FOV. And it is way less complex to build today than a full AESA. A very good transitional solution for what is meant to be a transitional jet.

[Mugatu]

Bingo!

 

One little fact: the modules cant turn, they are hard-fixed ;) Changing the direction of the beam is reached by signal timing.

Trying to divide the array of transmitter elements into "groups" with different radiation directions will 1.cause interference 2.require n^2 more operations to process every radar return (n - number of receiving elements).

[D-Scythe]

Bingo!

 

Thank you for proving my point. Despite having numerous opportunities to do so, the only thing you've come up with is that in your opinions "it's too difficult" for an AESA to generate multiple radar beams by dividing its antennae into smaller sub-arrays.

 

Despite you guys having the burden of proof, I've decided to accept it and post this, an excerpt from Stimson's Introduction to Airborne Radar (finally managed to get hold of a copy). I suppose a knock out in the 6th round/page of posts is better than nothing.

 

[Mugatu]

Yes if the aperture is designed for it, and what would be the impact of doing it!! poor performance so does NG do it for the APG-77, MESA for tracking and surveillance?

 

ps I don't know why the burden of proof is in our camp you have provided none either, now show one source where the APG-77 is shown to use multiple beams and not interleaving the main beam?

 

Thank you for proving my point. Despite having numerous opportunities to do so, the only thing you've come up with is that in your opinions "it's too difficult" for an AESA to generate multiple radar beams by dividing its antennae into smaller sub-arrays.

 

Despite you guys having the burden of proof, I've decided to accept it and post this, an excerpt from Stimson's Introduction to Airborne Radar (finally managed to get hold of a copy). I suppose a knock out in the 6th round/page of posts is better than nothing.

 

[Mugatu]

If you've got some spare cash download "F-22 Radar Development" by John A Malas.

[D-Scythe]

If you've got some spare cash download "F-22 Radar Development" by John A Malas.

 

Why? Does it disclose any classified information?

 

Yes if the aperture is designed for it, and what would be the impact of doing it!! poor performance so does NG do it for the APG-77, MESA for tracking and surveillance?

 

So...now you admit that it can be done, just that there's no point in doing it. Luckily, I don't need to change my position - again, the capability to generate multiple beams simultaneously may give rise to some interesting ECCM techniques.

 

Or not - from this point on, it's clearly conjecture, but from what we know publicly, an AESA can generate multiple beams from its array, so it's bad science to automatically assume that none of them do on the premise of "what's the point?"

 

ps I don't know why the burden of proof is in our camp you have provided none either, now show one source where the APG-77 is shown to use multiple beams and not interleaving the main beam?

 

Um, the burden of proof rests with you guys because you are challenging the pre-established notion that AESA can generate multiple beams. We actually know that an AESA is physically capable of doing so.

 

Which was specifically the point of contention. Specifically Post#30 of this thread - you said that AESA radars "don't divide the beam," in response to a post Alfa made earlier. Oh, and you made another post, #44, that contradicted my "broad" assertion that a (generic) "AESA antennae can generate multiple beams."

 

Now, you're asking for specific confirmation of whether the APG-77 array can generate multiple beams? Doesn't seem fair, does it?

[Mugatu]

it's ok to be wrong :P

 

I don't know what you're arguing. You have provided no evidence that the APG-77 cannot dedicate one group of AESA tiles to transmit in one direction and another group to transmit in another.

 

Also, the SPY-1 isn't even an AESA array - it's PESA. I'm talking about the SPY-3. And yes, it's like to be set up using multiple arrays, just like the SPY-1 - however, this STILL does not disprove the fact that one array can generate many radar beams simultaneously.

[D-Scythe]

I'm sorta looking for facts, theories, concepts...anything really, just not irrelevant semantics. Though if you wanna play that game, technically, you brought up "specific examples" first when you linked to the Northrop-Grumman website.

[Mugatu]

Last link (keyword "interleave") The paper above will give you facts. It's from the F-22 USAF System Project Office.

 

Doesn't matter, sorry I've pulled the thread off topic.

 

http://www.raytheon.com/products/stellent/groups/public/documents/content/cms04_018786.pdf

[D-Scythe]

Last link (keyword "interleave") The paper above will give you facts. It's from the F-22 USAF System Project Office.

 

Doesn't matter, sorry I've pulled the thread off topic.

 

http://www.raytheon.com/products/stellent/groups/public/documents/content/cms04_018786.pdf

 

 

...And once again, the fact that AESA's do time-share/interleave does not mean that it cannot generate multiple beams. They're 2 completely different techniques - there's no reason why the APG-77 or any other AESA can't have both agile beam steering and multiple radar beam generation.

[Rhen]

The interleaving that's being done is radar MODES - A/A & A/G. The APG-77 does produce MULTIPLE beams simultaneously (I provide no proof except that and will disclose no classified info). This radar is now in it's 4th generation, with future Raptors getting a refit to 77v4 standard. The 77(1) - (4) have the densest packaging of T/R elements (it doesn't use bricks, it uses tiles with 2 T/R units per tile vs 1 T/R unit per brick). The power output and frequency agility becomes more significant while maintaining LPI and degrading nothing. It's about software advancement (algorithms) and processing power onboard the aircraft - which the Raptor has in excess.

[D-Scythe]

The interleaving that's being done is radar MODES - A/A & A/G. The APG-77 does produce MULTIPLE beams simultaneously (I provide no proof except that and will disclose no classified info). This radar is now in it's 4th generation, with future Raptors getting a refit to 77v4 standard. The 77(1) - (4) have the densest packaging of T/R elements (it doesn't use bricks, it uses tiles with 2 T/R units per tile vs 1 T/R unit per brick). The power output and frequency agility becomes more significant while maintaining LPI and degrading nothing. It's about software advancement (algorithms) and processing power onboard the aircraft - which the Raptor has in excess.

 

Didn't know there were APG-77V3 and V4 variants. Thanks for the info. BTW, I do remember hearing that some AESA radars do rely exclusively on interleaving between targets, and actually don't come with a capability to generate multiple beams (at least in their baseline version)...but clearly you're the Poobah bear here.

 

Hey Mugey, I bolded the part of interest in Rhen's post, you know, just in case you missed the big caps.

[tflash]

Right. It is that simple. I could pump up the number of scientific articles that discuss multiple beams with AESA systems, but I do not think a Russian forum is the place to do so. Mugatu, just accept the fact that 1) multiple beams on AESA is currently technologically achievable and 2) the APG-77 does the trick.

 

We ain't see nothing yet: AESA allows you to use the same array of T/R modules to do radar, ECM and ECCM functions. It saves on mechanical parts and is incredibly reliable.

 

And even better, suppose that it only uses interleaving, like I guess is the case with the APG-79 radar in the Super Hornet, this is still so fast (near speed of light) that it actually *amounts* to having the capability of multiple simultanious beams.

[Mugatu]

Alright yes maybe for some little sub modes :P but not for searching and tracking as the first comments indicated and I too will not release class information :P. The paper above referenses no use of multiple beams and it's probably has the most unclass info you'll find on the APG-77.

 

I think your all Raptor fan boys haha Just kidding.

 

Again the TASKING of the main beam is used for the fast majority of the modes of an AESA radar, that includes searching and tracking.

 

I'm yet to see any info on the APG-77, MESA or CEAFAR that states anything else ...

 

 

"Waveform

Design:

Increased processing resources and active

probability of intercept in building these submodes."

 

...

 

Radar activity is controlled by an avionics level sensor

manager which provides commands via a high speed data bus.

System parameters such as search waveform selection, scan volume

size, desired track accuracy, and timeline prioritization are examples

of sensor management commands.

 

 

...

 

At the heart of the system is the array subsystem. The array is

designed to provide electronically scanned beam coverage within a

conical volume normal to the antenna face. The array incorporates

4 forward looking guard antennas with any two connected and in

operation at any one time. The basic building block for the antenna

is the “subarray”. This is an assembly of mechanical and electrical

parts formed in a long slat which extends the total diameter of the

antenna. Several subarray lengths will be used to form the circular

shape of the antenna. The subarray consists of a single vacuum

brazed cold-plate on which RF manifolds, logic/power manifolds,

transmit and receive modules, and a radiator strip are mounted. All

subarrays contain the same functional components. The only

difference is in length, hence they will vary in the number of T/R

modules and radiators they accommodate. The subarrays, when

assembled with T/R modules, signal manifolds, and radiators, are

mounted to an enclosure to form the bulk of the completed antenna.

The beam steering controller computes phase and amplitude for the

individual active array T/R modules based on beam shape and scan

commands from the radar operational flight program (OFP).

...

The last quote is what makes multiple beams possible for sub modes, maybe LPI but there is other ways of doing that without sacrificing range and tgt ambiguity and I'll give you multiple beams from the side arrays when/if installed ...

 

Right. It is that simple. I could pump up the number of scientific articles that discuss multiple beams with AESA systems, but I do not think a Russian forum is the place to do so. Mugatu, just accept the fact that 1) multiple beams on AESA is currently technologically achievable and 2) the APG-77 does the trick.

 

We ain't see nothing yet: AESA allows you to use the same array of T/R modules to do radar, ECM and ECCM functions. It saves on mechanical parts and is incredibly reliable.

 

And even better, suppose that it only uses interleaving, like I guess is the case with the APG-79 radar in the Super Hornet, this is still so fast (near speed of light) that it actually *amounts* to having the capability of multiple simultanious beams.

array technology have added waveform adaptability design options

that are not available to conventional systems. Avionics level

control of radar measurement tasking provides a software interface

which lends itself to radar “submodes of operation” offering the

pilot more flexibility in the cockpit. Trades were conducted in the

area of search and track mode design to explore the implications of

timeline management, target measurement maintenance, and low

[Alfa]

Alright yes maybe for some little sub modes :P but not for searching and tracking as the first comments indicated...

 

Which first comments would that be?

 

You will notice that this whole thread concerns the Su-35 and that the bit which sparked this AESA discussion was my comment about the additional potential of this over a PESA design. In this connection there would be no reason to mention the benefits of electronic beam pointing since this is a common feature of PESA and AESA.

 

Aside from improved technology and reliability, the whole point to an AESA is exactly the potential for increased functionality and "multi-tasking" - i.e. simultaneous use of the array for adverse functions and the versatility provided via the software based nature of these.

[Mugatu]

Your right there is not much difference in performance between and AESA and PESA radar, the real benefit is operational availability and the weight savings. I think you gave an example where you could use multiple beams to track tgts at the extremes of the scan zone where and in practice this is done via interleaving the tasks your performing ... and yes just as timeslicing on a single CPU you can consider it working in parallel. Where as in a mechanical array you have to wait for the anntena to move however there is still the same problems that need to be considered dwell time range resouliton etc etc etc Where the Raptor excells, this is done in the main processor not the radar it self, thus you can collect alot more inforamation and try to correlate the data. Not really a benefit of AESA over PESA, more to do with the sensor interface and the avionics architecture. I can't say I've seen the SU-35 avionics architecutre.

 

The poor guy writing the code is looking at what time budget is available for the main array and the current tasks needing to be performed. Anyway enough said, hopefully people don't think that there are 1000 little beams being bumped out by an AESA or PESA as you read in so may forums.

 

Which first comments would that be?

 

You will notice that this whole thread concerns the Su-35 and that the bit which sparked this AESA discussion was my comment about the additional potential of this over a PESA design. In this connection there would be no reason to mention the benefits of electronic beam pointing since this is a common feature of PESA and AESA.

 

Aside from improved technology and reliability, the whole point to an AESA is exactly the potential for increased functionality and "multi-tasking" - i.e. simultaneous use of the array for adverse functions and the versatility provided via the software based nature of these.

[Kusch]

Another Hig-res gallery:

 

http://www.sukhoi.org/gallery/?gallery_id=110&cur_gallery_id=110

[Rhen]

Your right there is not much difference in performance between and AESA and PESA radar, the real benefit is operational availability and the weight savings.

 

You're kidding me, right? I'm no EE, I'm just a pilot, but that statement shows that you haven't considered the differences in design, architecture, and operational capability:

 

PESA - Passive Electronically Steered Array or passive phased array radar

PRO's:

Agile electronically steered beam

Multiple antenna elements, as with conventional planar array

Low weight compared to MSA (mechanically steered array)

High power beam - since it has a single beam usually using a TWT (travelling wave tube)

Beam width, shape, and obviously direction can be finely controlled

Much smaller radar signature with smaller side lobes - less apt to be jammed

Modes (A/A & A/G) can be interleaved and other modes can be time shared

 

CON's:

High power beam using a TWT - can only produce one beam at any given time and if the TWT is jammed, so long radar.

TWTs degrade with time and need to be replaced sooner than T/R moduels in AESA

Single frequency beam, as opposed to multiple simultaneous frequencies.

Not as expensive as AESA

Not as many problems with heat dissipation

 

AESA - Active Electronically Scanned Array

PRO's:

Same as above but because it doesn't use a/multiple TWTs but a T/R module:

Each antenna (receiver) has a transmitter behind it (low power) - A T/R module, & each AESA radar is made up of thousands of T/R units. This allows AESA radars the following benefits:

Each T/R or group of T/R units can function at different frequencies = multiple beams, more jam resistance, can sustain multiple T/R unit failures without significantly affecting radar performance, higher MTBF over previous radar types. These multiple beams can have different functions: X-band tracking, L-band scanning, IFF, EW, and NCTR all simultaneously (good luck trying that PESA!) Did I mention LPI? Well what's the use of putting a PESA on a stealth aircraft? Each T/R module can transmit at varying frequencies, strength just below Bandit RWR detection levels, PRFs, pulse forms, and all this variation made rapidly will confuse RWR sets at higher outputs, or be undetectable since they last a brief moment (shows up as noise and is not displayed, a false alarm, or doesn't show up at all). This is in contrast with a PESA scanning at kilowatt level power in a single frequency pulse.

Better NCTR based on 3D synthetic aircraft signature rather than fan blades in an engine - thus allowing more rapid and all-aspect NCTR ID of targets.

Small side lobes as well, but with less power per T/R group transmitting, it has even smaller side lobes with attendant jam resistance.

 

Let's not even mention that the AESA radar makes more than half of what the Raptor does operationally a secret. Can you say Electronic Attack and soft killing airborne sensor systems such as A/A missiles or search and fire control radars to name a few unclassified functions coming out of recent publications.

 

CON's:

Lower power beam can theoretically decrease fire control ranges over higher power beam forms (but in reality, this is not significant to operational ability)

EXPENSIVE T/R units (or MMICs - microwave monolithic integrated circuits), very complex to mass produce. Considering that each aircraft needs hundreds - to several thousand T/R units - an inexpensive mass-production capability needs development = for which the Russians (and until recently Europe) do not have. Until anyone can reliably turn out T/R units in mass quantity - AESA radars are superfluous. Consider that the Raptor program requires 3/4 million T/R units if the Raptor is ordered in numbers that the USAF wants.

HEAT - MMICs are like any IC and want to operate cold. Requires active cooling - usually fluid like your CPU or video card :smilewink:

Dubious savings of maintenance functions - while it's easy and quick to replace a T/R unit as opposed to a magnetron or TWT, the liquid cooling system needs to have excess capability to deal with longer active cycles (search and fire control functions, and obviously EA).

 

 

I think you gave an example where you could use multiple beams to track tgts at the extremes of the scan zone where and in practice this is done via interleaving the tasks your performing ... and yes just as timeslicing on a single CPU you can consider it working in parallel. Where as in a mechanical array you have to wait for the anntena to move however there is still the same problems that need to be considered dwell time range resouliton etc etc etc

 

Read above. You still fail to see that this is possible, I guess. So, don't believe me or other reputable sources... just go with your first instinct, man!:smartass: After all, we can't all be right like you, right?

 

Where the Raptor excells, this is done in the main processor not the radar it self, thus you can collect alot more inforamation and try to correlate the data. Not really a benefit of AESA over PESA, more to do with the sensor interface and the avionics architecture. I can't say I've seen the SU-35 avionics architecutre.

 

True, the Raptor has excess processing power with enough system redundancy as well. Even at peak, the processor array works only at less than 3/4 of its max (like it's underclocked) potential. The thing that makes AESA work is processing power and software. Without that, there's no AESA.

 

Anyway enough said, hopefully people don't think that there are 1000 little beams being bumped out by an AESA or PESA as you read in so may forums.

 

No, not a thousand, but definitely more than one!:megalol:

 

Sorry Alfa for continuing to take this thread OT!:blush:

[EvilBivol-1]

Just a note, the Su-35 demonstrator flew again on Thursday.

[SuperKungFu]

Another Hig-res gallery:

 

http://www.sukhoi.org/gallery/?gallery_id=110&cur_gallery_id=110

 

 

Thanks for the extra photos. Now this is what I'm talking about. Russia needs more of these air-to-air hi-res shots of their flankers. Its hard to come across these beauty.

[Mugatu]

Definitely a sweet looking aircraft, gotta love the rearward facing array!

[4c Hajduk Veljko]

I like that EA missile on Su-32.

 

http://www.sukhoi.org/img/gallery/wallpaper/SU-32-otl.jpg

[Pilotasso]

Please...everybody resist the temptation ok? :lol: